[PLUG] Firefox add-ons dropped, can't re-install

[Rich Shepard]

On Sat, 4 May 2019, Richard England wrote:

> I believe this may be the answer to "what happened"
> https://discourse.mozilla.org/t/certificate-issue-causing-add-ons-to-be-disabled-or-fail-to-install/39047

Thanks, Richard. This looks like the release first, fix it later coding
pattern.

FWIW, that URL tells us to go to Edit -> Preferences -> Privacy & Security
-> Allow Firefox to install and run studies. But, that option is disabled
here. Oh, well.

Regards,

Rich